Wildfire effects in mixed conifer forests from Northwestern Mexico: Possible targets for restoration

In contrast to a few isolated forests in northern Mexico, most forests in the western Untied States have been significantly modified by fire suppression, harvesting, and livestock grazing. This has increased their fire hazards and many are in need of restoration, particularly those that once experience frequent, low-moderate intensity fire regimes. Understanding reference conditions is challenging because we have few intact forests functioning under the continuing influence of climate variation, insects, diseases, and frequent fires. This presentation summarizes the effects of a 2003 wildfire in an intact Jeffrey pine-mixed conifer forests in northern Baja California, Mexico. This forest has never been harvested and fire suppression did not begin until the 1970’s. The wildfire burned at the end of a multiple-year drought but tree mortality after fire was very low. Many areas within the wildfire perimeter were not burned. Wildfire effects had a great deal of heterogeneity and subsequent fires would also be heterogeneous because of large variations in forest structure and fuels. The forests of the western United States with similar species, topography, and disturbance regimes would be expected to have similar variation prior to fire exclusion. Restoration of similar forests should not use uniform restoration targets, methods must be developed to incorporate variation in desired conditions. Increasing the amount of area burned in the western United States using wildfire fire use should begin to create heterogeneous forest structure but more research is needed to more fully understand fire effects after decades of fire exclusion.